THE ORIGIN OF ESTRONE SULFATE IN NORMAL AND MALIGNANT BREAST TISSUES IN POSTMENOPAUSAL WOMEN

Conversion of oestrone sulphate to oestrone has been suggested to make a major contribution to the level of oestrone found in breast tissues. In order to examine the ability of breast tissues to take up oestrone sulphate (E1S), H-3 E1S or E1-S-35 was infused 'into postmenopausal women with advanced breast cancer. For 3 subjects infusion of H-3 E1S was repeated after treatment with Danazol, a potential inhibitor of oestrone sulphatase activity. After infusion of H-3 E1S significant levels of H-3 E1S were detected in normal and malignant breast tissues (tissue:plasma ratios 0.14+/-0.13 and 0.24+/-0.12 respectively, mean+/-S.D., n=5). Similar H-3 E1S tissue:plasma ratios were detected after infusions of H-3 E1 indicating that the H-3 E1S detected in breast tissues after infusion of H-3 E1S may have originated from the hydrolysis of H-3 E1S in tissues other than the breast, with subsequent uptake and sulphation in breast tissues. After infusion of E1-S-35 no significant levels of radioactivity were detectable in normal or malignant breast tissues. Treatment with Danazol had no significant effect on tissue levelS of H-3 E1S or on the CR(E1S E1) or MCR-E1S. It is concluded that oestrone sulphate, as such, is not taken up by breast tissues and that any contribution that oestrone sulphate makes to the oestrogen content of breast tissues will depend upon prior hydrolysis.